Astronomy and Astrophysics, volume 624A, 44-44 (2019/4-1)
Be and O in the ultra metal-poor dwarf 2MASS J18082002-5104378: the Be-O correlation.
SPITE M., BONIFACIO P., SPITE F., CAFFAU E., SBORDONE L. and GALLAGHER A.J.
Abstract (from CDS):
Context. Measurable amounts of Be could have been synthesised primordially if the Universe were non-homogeneous or in the presence of late decaying relic particles.
Aims. We investigate the Be abundance in the extremely metal-poor star 2MASS J1808-5104 ([Fe/H]=-3.84) with the aim of constraining inhomogeneities or the presence of late decaying particles.
Methods. High resolution, high signal-to-noise ratio (S/N) UV spectra were acquired at ESO with the Kueyen 8.2m telescope and the UVES spectrograph. Abundances were derived using several model atmospheres and spectral synthesis code.
Results. We measured log(Be/H)=-14.3 from a spectrum synthesis of the region of the Be line. Using a conservative approach, however we adopted an upper limit two times higher, i.e. log(Be/H)←14.0. We measured the O abundance from UV-OH lines and find [O/H]=-3.46 after a 3D correction.
Conclusions. Our observation reinforces the existing upper limit on primordial Be. There is no observational indication for a primordial production of 9Be. This places strong constraints on the properties of putative relic particles. This result also supports the hypothesis of a homogeneous Universe, at the time of nucleosynthesis. Surprisingly, our upper limit of the Be abundance is well below the Be measurements in stars of similar [O/H]. This may be evidence that the Be-O relation breaks down in the early Galaxy, perhaps due to the escape of spallation products from the gas clouds in which stars such as 2MASS J1808-5104 have formed.
© M. Spite et al. 2019
stars: abundances - binaries: spectroscopic - stars: Population II - stars: individual: 2MASS J18082002-5104378
VizieR on-line data:
<Available at CDS (J/A+A/624/A44): oxy.dat>
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